So basically try this:
defmodule MyApp.Application do
use Application
def start(_type, _args) do
IO.inspect(Application.get_all_env(:myapp))
# ...
end
end
stefanchrobot
1
jononomo
Ok, so I had assumed that runtime.exs is evaluated at runtime, but I had the following lines in runtime.exs:
config :myapp,
jon: "jon-runtime"
IO.inspect('in runtime.exs...')
IO.inspect(Application.fetch_env(:myapp, :jon))
and when I started the app via mix phx.server I was seeing the following output in my terminal:
'in runtime.exs...'
{:ok, "jon-dev"}
Since I had set the variable “jon” to “jon-dev” in my dev.exs file, it appeared to me that runtime.exs was not overwriting this value at runtime, which is when I thought runtime.exs was running.
Can anyone explain why I see the output
'in runtime.exs...'
{:ok, "jon-dev"}
if runtime.exs is executed only at runtime and not at compile time?
Or is runtime.exs evaluated but not executed, or something like that, at compile time? What is going on there when I set the value to “jon-runtime” in runtime.exs and then immediately inspect it and have it print out “jon-dev” instead?
0
Nicd
This is an implementation detail: the config ... line actually does not set the application env at that point, it puts values to the process dictionary with Process.put. The application env is created later when the system starts proper. Thus if you want to share some common values inside runtime.exs (or other config files), you must put them in regular variables.
Try inspecting the values inside your application.ex start-callback. That function is executed at runtime and you should see the correct values there (and any other function executed at runtime).
4
emoragaf
I think the easiest way that you can check your config here, would be to start the app like iex -S mix and call Application.fetch_env(:myapp, :jon) inside iex
2
jononomo
Ok, perfect. This is what had me confused. I have a much better understanding of what is happening now. It seems that runtime.exs is evaluated after compilation, but before “the system starts proper” – so it’s in that liminal, hard-to-understand space.
0
maz
lud
John-Goff
The releases.exs file was released in elixir 1.9, this was the first attempt at runtime config but it only applied to releases and not in dev. Elixir 1.11 introduced runtime.exs which runs in both dev and release mode.
4